1. Field of the Invention
The present invention relates to a drawing apparatus, and a method of manufacturing an article.
2. Description of the Related Art
As one of lithography apparatuses used to manufacture, for example, semiconductor devices, a charged particle beam drawing apparatus which draws a pattern on (transfers it onto) a substrate with a charged particle beam (electron beam) has been known. Charged particle beam drawing apparatuses are roughly classified into a single-beam drawing apparatus which performs drawing with one charged particle beam, and a multibeam drawing apparatus which performs drawing with a plurality of charged particle beams. A multibeam drawing apparatus is attracting a great deal of attention as an apparatus available for mass production because the throughput is expected to improve more than a single-beam drawing apparatus.
A charged particle beam drawing apparatus deflects (scans) a charged particle beam along a design coordinate system set on a substrate, and controls ON/OFF of the irradiation (blanking) of the substrate with the charged particle beam, thereby drawing a pattern on the substrate. A charged particle beam drawing apparatus converts design data representing a pattern (circuit pattern) to be drawn on a substrate into drawing data, and controls ON/OFF of the irradiation of the substrate with a charged particle beam based on the drawing data, regardless of whether the charged particle beam drawing apparatus is of the single-beam or multibeam type. Note that the design data is CAD data or vector data, and the drawing data is bitmap data. Japanese Patent Laid-Open No. 8-505003 proposes a technique of converting CAD data or vector data (design data) into bitmap data.
In recent years, with an increase in pattern dimension accuracy required for a charged particle beam drawing apparatus, that is, a reduction in minimum line width of the pattern, the size of drawing data (data volume) required to draw a pattern in a region corresponding to one chip is becoming enormous. On the other hand, to utilize a charged particle beam drawing apparatus for mass production, an improvement in throughput is necessary, so a large amount of data including such drawing data must be processed at high speed. However, in terms of data size, it is difficult to hold design data (CAD data or vector data) upon bitmap rasterization in advance, that is, in the form of drawing data (bitmap data). Therefore, the charged particle beam drawing apparatus stores data representing a pattern in its internal storage unit as design data, reads out the design data stored in the storage unit in the order of drawing in drawing a pattern, and performs bitmap rasterization (conversion) into drawing data.
In the related art technique, the design data includes not only a pattern to be drawn on a substrate but also a mark such as an alignment mark or an inspection mark, so it is impossible to change the mark drawing position or drawing timing immediately before drawing a pattern. However, to draw a pattern as fine as the recently required pattern, it is necessary to change the mark drawing position and drawing timing in accordance with the state of a substrate and that of a charged particle beam drawing apparatus.
The case wherein, for example, an alignment mark (inspection mark) is drawn in a region in which the flatness of a substrate is poor as dust has adhered to the front or back surface of the substrate will be considered. In this case, when the charged particle beam and the substrate are aligned using the alignment mark, the alignment error may increase. In addition, it takes a longer time for a charged particle beam drawing apparatus than for an exposure apparatus to draw a pattern. Therefore, due to a shift between the drawing timing of a main pattern (critical pattern) and that of an alignment mark, the alignment error for the main pattern in a subsequent drawing (exposure) operation may increase.